Is there any Quebec rider here who can tell me how much it will cost to register a new KLR bought from a dealer ?
I read something about 'Insurance contribution' which is quite expensive.
Can that be circumvented by one of the cheaper private insurers ?

Could I buy, and ride over to BC on a 10 day temp reg to register for less money in BC ?

Hmmmm...... Don't know enough about a non resident purchasing and insuring a bike. I do know however, that BC is not cheap to insure a bike. Much cheaper in Alberta. Have you tried a search on Horizon's Unlimited? There is a ton of information there about accomplishing what you are trying to do.